This invention relates generally to the filling of brachytherapy needles with radioactive seeds and spacers, and more specifically concerns an apparatus for loading and visually verifying radioactive seeds and spacers in a brachytherapy needle.
Brachytherapy is a treatment regimen for prostate cancer involving the use of radioactive seeds/pellets and spacing elements (the spacing elements are not radioactive) in hollow, stainless steel needles. The loaded needles are inserted into the prostate in a preselected pattern specific to a given patient. The radioactive pellets are usually iodine No. 125 and/or palladium No. 103.
The brachytherapy technique in general is well known and is described in U.S. Pat. No. 5,871,448, which is hereby incorporated by reference, as well as numerous technical articles in various medical journals.
The needles are loaded individually with radioactive seeds and spacers, typically prior to insertion. Until recently, the radioactive seeds and spacing elements were loaded by hand, using tweezers specially adapted for handling the radioactive seeds. In this manual method, the technician/user grasps the seeds and the spacers alternately one by one with the tweezers and drops them (seed, spacer, seed, etc.) into the hollow needle. This manual loading is done behind a shield to protect the body and head of the user from exposure to the radiation from the seeds/pellets. The manual method has several disadvantages, including an inability to verify the correct loading of the needle, since the stainless steel needles are opaque. In addition, the hand and fingers of the user are still exposed to radiation. While considerable skill is necessary to perform the manual loading operation quickly, an expert operator can load as many as 25 needles in 10 minutes.
Devices have since been developed, however, which assist significantly in the loading of brachytherapy needles. In one case, tweezers are used to position radioactive seeds and spacers in a positioning tube mounted on a support member. The tube is transparent, which permits the arrangement of the seeds to be verified. The tube is then rotated on the support into alignment with a brachytherapy needle which is mounted at one side of the support and extends outwardly therefrom. The seeds and spacers are then moved horizontally by an insertion element into the needle. This device, however, is subject to jamming; the user is exposed to radiation from the seeds, and the extending needle creates a hazard. In addition, loading of brachytherapy needles with this device is time consuming.
In another development, the radioactive seeds and spacers are moved by a pusher tool from open wells in a tray to a horizontal groove in the tray, such that they are lined up in a desired order. The needle is positioned at one end of the groove, extending horizontally. The lined-up seeds and spacers in the groove can then be pushed into the needle by an insertion element. This device also has the disadvantage of exposure of the hands of the user to radiation and the chance of a needle stick. In a variation of this device, a lead acrylic shield is positioned over the tray, protecting the user fully from the radiation.
In still another development, the seeds and spacers are drawn into a positioning tube by a vacuum device and then moved from there into the brachytherapy needle. This device is somewhat cumbersome, however, and the complete sequence of actions to the completion of loading requires a substantial amount of time. The user""s hands, moreover, are still exposed to radiation.
All of the above devices require more time than is desirable to load the needles. It is desirable to have a device by which a brachytherapy needle can be reliably and quickly loaded, with minimal or no exposure of the user to radiation, while permitting convenient visual inspection of the loaded seeds.
Accordingly, the present invention is an apparatus for loading radioactive seeds and spacers into a needle for use in the treatment of cancer in a localized portion of the body, comprising: a tray assembly which receives radioactive seeds and spacers, wherein the tray assembly includes a funnel portion into which the received seeds and spacers can be moved by use of a moving member, such as a small paddle; a visualizing and positioning assembly for said seeds and spacers located beneath the funnel portion of the tray assembly, the visualizing assembly including a vertically oriented slot into which the seeds and spacers fall by gravity after being moved into the funnel portion, the visualizing assembly being partially transparent to permit a user to verify the arrangement of seeds and spacers in the slot; and a control element in the visualizing and positioning assembly, permitting release of the seeds and spacers into a hollow needle.